A battery is an energy storage device used to store and supply electrical energy, usually consisting of one or more electrochemical cells that convert stored chemical energy to electrical energy. A plurality of electrochemical cells are often stacked together side-by-side and electrically connected together in series or parallel to form a battery pack, or battery module. One or more battery modules can be secured on a pack base for installation on, for example, an electric or hybrid vehicle, allowing the vehicle to utilize the energy from the battery modules to power the vehicle's motor and other electrical systems.
Typically, the cells of a battery module are held together in a stack by a mechanical fixation assembly, sometimes referred to as a cage. The cage provides structural support to the cells with at least one metal restraint band conforming around a stack of cells. Portions of the metal restraint band are typically welded, riveted, or screwed together. The cage further include flanges through which threaded fasteners are installed to secure the cage and cells to a battery pack base.
The known mechanical fixation assembly has drawbacks. For example, assembling and welding the cage imposes burdensome costs on manufacturers. Furthermore, weight reduction on electric and hybrid vehicles is desirable to increase energy efficiency and range of the vehicles, and size reduction of batteries is also needed because space on the vehicles is at a premium. However, the metal bands of traditional cages increase the overall weight and size of the module. Additionally, battery cells expand and contract due to chemical reactions during cycling, and during expansion, stresses are applied by the cells at points of contact between the cells and the band, and at points of contact between each adjacent cell. Peak stresses concentrated at the points of contact may cause deformation, fracture and failure of the cell dielectric coating or casing, leading to short circuits or reduced performance and overall life of the cells. There is a need for another method of cell fixation.